Your VPN Tunnel Sharing setting under Advanced Properties in the VPN Community is probably set to "pair of hosts", which creates a unique Phase 2 IPSEC tunnel for every possible combination of hosts that try to use the VPN. "Pair of subnets" is more appropriate; if that is already selected consider the "one tunnel per gateway pair" setting. Be careful changing this setting though as it can have a wide impact on VPN connectivity, best to do it during a maintenance window.